Category Archives: Science

You’ll recall yesterday’s astropic of the Ring nebula. Well, M57 is a lot more complicated than it appears when you break out the big lens. To wit:

The easily visible central ring is about one light-year across, but this remarkably deep exposure – a collaborative effort combining data from three different large telescopes – explores the looping filaments of glowing gas extending much farther from the nebula‘s central star. This composite image includes red light emitted by hydrogen as well as visible and infrared light. The Ring Nebula is an elongated planetary nebula, a type of nebula created when a Sun-like star evolves to throw off its outer atmosphere to become a white dwarf star. The Ring Nebula is about 2,500 light-years away toward the musical constellation Lyra.

(Image: Hubble, Large Binocular Telescope, Subaru Telescope; Composition & Copyright: Robert Gendler)

apod

Behold M57, aka, the Ring nebula – about one light-year across and 2,500 light-years away – the most famous celestial circle outside the rings of Saturn.

Its classic appearance is understood to be due to our own perspective, though. The recent mapping of the expanding nebula’s 3-D structure, based in part on this clear Hubble image, indicates that the nebula is a relatively dense, donut-like ring wrapped around the middle of a (American) football-shaped cloud of glowing gas. The view from planet Earth looks down the long axis of the football, face-on to the ring. Of course, in this well-studied example of a planetary nebula, the glowing material does not come from planets. Instead, the gaseous shroud represents outer layers expelled from the dying, once sun-like star, now a tiny pinprick of light seen at the nebula’s centre. Intense ultraviolet light from the hot central star ionises atoms in the gas. 

(Image: NASA, ESA, Hubble Legacy Archive; Processing: Judy Schmidt)

apod

Behold: comet dust raining down last week in a composite shot taken during the peak night of the annual Perseid meteor shower. To wit:

The umbrella was not needed as a shield from meteors, since they almost entirely evaporate high in the Earth’s atmosphere. Many of the component images featured individual Perseids, while one image featured the foreground near Jiuquan City, Gansu Province, China. The stellar background includes the central band of our Milky Way Galaxy, appearing nearly vertical, as well as the planets Jupiter and Saturn on the left. Although the comet dust particles are traveling parallel to each other, the resulting shower meteors clearly seem to radiate from a single point on the sky — the radiant in the eponymous constellation Perseus. The image captured so long an angular field that the curvature of the sky is visible in the trajectory of the Perseids. 

(Image: Luo Hongyang)

apod

In the first part of a new series on the human body, German educational design studio Kurzgesagt explores the human immune system – an extensive biological system which…

…consists of hundreds of tiny and two large organs, it has its own transport network spread throughout your body. Every day it makes hundreds of billions of fresh cells. It is not some sort of abstract entity. Your immune system is YOU. Your biology protecting you from the billions of microorganisms that want to consume you and from your own perverted cells that turn into cancer.

Previously: The Biggest Black Hole In The Universe

What does fire look like without gravity? Like this. To wit:

In the gravity on Earth, heated air rises and expands, causing flames to be teardrop shaped. In the microgravity of the air-filled International Space Station (ISS), however, flames are spheres. Fire is the rapid acquisition of oxygen, and space flames meet new oxygen molecules when they float by randomly from all directions — creating the enveloping sphere. In the featured image taken in the ISS’s Combustion Integration Rack, a spherical flame envelopes clusters of hot glowing soot. Without oxygen, say in the vacuum of empty space, a fire would go out immediately. The many chemical reactions involved with fire are complex, and testing them in microgravity is helping humanity not only to better understand fire — but how to put out fire, too.

(Image: NASA)

apod

How best to watch a meteor shower? Well, later this week, the annual Perseid Meteor Shower will hit its peak. So what next for the avid skywatcher? To wit:

One thing that is helpful is a dark sky, as demonstrated in the featured composite image of last year’s Perseids. Many more faint meteors are visible on the left image, taken through a very dark sky in Slovakia, than on the right image, taken through a moderately dark sky in the Czech Republic. The band of the Milky Way Galaxy bridges the two coordinated images, while the meteor shower radiant in the constellation of Perseus is clearly visible on the left. In sum, many faint meteors are lost through a bright sky. Light pollution is shrinking areas across our Earth with dark skies, although inexpensive ways to combat this might be implemented.

(Image: Tomas Slovinsky (Slovakia) & Petr Horalek (Czech Republic; Institute of Physics in Opava)

apod

Behold: the picturesque result of cosmic dust clouds crossing a rich field of stars in a telescopic vista near the northern boundary of Corona Australis, the Southern Crown.  To wit:

Less than 500 light-years away the dust clouds effectively block light from more distant background stars in the Milky Way. Top to bottom the frame spans about 2 degrees or over 15 light-years at the clouds’ estimated distance. At top right is a group of lovely reflection nebulae cataloged as NGC 6726, 6727, 6729, and IC 4812. A characteristic blue color is produced as light from hot stars is reflected by the cosmic dust. The dust also obscures from view stars in the region still in the process of formation. Just above the bluish reflection nebulae a smaller NGC 6729 surrounds young variable star R Coronae Australis. To its right are telltale reddish arcs and loops identified as Herbig Haro objects associated with energetic newborn stars. Magnificent globular star cluster NGC 6723 is at bottom left in the frame. Though NGC 6723 appears to be part of the group, its ancient stars actually lie nearly 30,000 light-years away, far beyond the young stars of the Corona Australis dust clouds.

(Image: Vikas Chander)

apod

Behold: the battered, pockmarked southern highlands of the Moon – home to impact sites old and young. To wit:

Captured on July 20, the lunar landscape features the Moon’s young and old, the large craters Tycho and Clavius. About 100 million years young, Tycho is the sharp-walled 85 kilometre diameter crater near centre, its 2 kilometre tall central peak in bright sunlight and dark shadow. Debris ejected during the impact that created Tycho still make it the stand out lunar crater when the Moon is near full, producing a highly visible radiating system of light streaks, bright rays that extend across much of the lunar near side. In fact, some of the material collected at the Apollo 17 landing site, about 2,000 kilometres away, likely originated from the Tycho impact. One of the oldest and largest craters on the Moon’s near side, 225 kilometer diameter Clavius is due south (above) of Tycho. Clavius crater’s own ray system resulting from its original impact event would have faded long ago. The old crater’s worn walls and smooth floor are now overlayed by smaller craters from impacts that occurred after Clavius was formed. Observations by the Stratospheric Observatory for Infrared Astronomy (SOFIA) published in 2020 found water at Clavius. Of course both young Tycho and old Clavius craters are lunar locations in the science fiction epic 2001: A Space Odyssey.

(Image: Eduardo Schaberger Poupeau)

apod

Behold: a flashing object that streaked across the sky against the backdrop of the Milky Way nearly three years ago, leaving a bright green trail that took 30 minutes to dissipate. To wit:

Given the day, August 12, and the direction, away from Perseus, it was likely a small bit from the nucleus of Comet Swift-Tuttle plowing through the Earth’s atmosphere — and therefore part of the annual Perseids meteor shower. The astrophotographer captured the fireball as it shot across the sky in 2018 above a valley in Yichang, Hubei, China. The meteor’s streak, also caught on video, ended near the direction of Mars on the lower left. Next week, the 2021 Perseids meteor shower will peak again. This year the Moon will set shortly after the Sun, leaving a night sky ideal for seeing lots of Perseids from dark and clear locations across planet Earth.

(Image: Dandan Huang)

apod